Configuring Uplink Subframes and Controlling Power in a Carrier Aggregation System When the Dci Format Has First or Second Identifiers

1. A method for a user equipment (UE) to manage a transmission power for a random access in a wireless communication system, the method comprising: determining a transmission power of a first physical random access channel (PRACH) for a first cell group, the first cell group consisting of a primary cell (PCell) and zero or more secondary cells (SCells); determining a transmission power of a second PRACH for a second cell group, the second cell group consisting of one or more SCells only; and when a condition including (i) the first PRACH overlaps in time domain with the second PRACH, and (ii) a total transmission power of the first and second PRACHs exceeds a threshold is satisfied, restricting the transmission power of the second PRACH for the second cell group such that a new total transmission power of the first and second PRACHs does not exceed the threshold.

2. The method of claim 1 , wherein the first cell group is managed by a first base station (BS) and the second cell group is managed by a second BS different from the first BS, and the UE has communication connectivity both with the first and second BSs.

3. The method of claim 1 , wherein the first BS manages and performs an radio resource control (RRC) function associated with the UE.

4. The method of claim 1 , wherein when the first PRACH overlaps in time domain with the second PRACH, and the total transmission power of the first and second PRACHs exceeds the threshold, the first PRACH is transmitted using the determined transmission power of the first PRACH.

5. The method of claim 1 , wherein when the first PRACH overlaps in time domain with the second PRACH, and the total transmission power of the first and second PRACHs exceeds the threshold, a transmission of the second PRACH is dropped.

6. The method of claim 1 , wherein when the first PRACH overlaps with the second PRACH in a time domain, and the total transmission power of the first and second PRACHs exceeds the threshold, the determined transmission power of the second PRACH is reduced such that the new total transmission power of the first and second PRACHs does not exceed the threshold.

7. The method of claim 1 , wherein the threshold is a maximum power limit.

8. A user equipment (UE) configured to manage a transmission power for a random access in a wireless communication system, the UE comprising: a radio frequency (RF) unit; and a processor, wherein the processor is configured to: determine a transmission power of a first physical random access channel (PRACH) for a first cell group, the first cell group consisting of a primary cell (PCell) and zero or more secondary cells (SCells); determine a transmission power of a second PRACH for a second cell group, the second cell group consisting of one or more SCells only; and when a condition including (i) the first PRACH overlaps in time domain with the second PRACH, and (ii) a total transmission power of the first and second PRACHs exceeds a threshold is satisfied, restrict the transmission power of the second PRACH for the second cell group such that a new total transmission power of the first and second PRACHs does not exceed the threshold.

9. The UE of claim 8 , wherein the first cell group is managed by a first base station (BS) and the second cell group is managed by a second BS different from the first BS, and the UE has communication connectivity both with the first and second BSs.

10. The UE of claim 8 , wherein the first BS manages and performs an radio resource control (RRC) function associated with the UE.

11. The UE of claim 8 , wherein when the first PRACH overlaps in time domain with the second PRACH, and the total transmission power of the first and second PRACHs exceeds the threshold, the first PRACH is transmitted using the determined transmission power of the first PRACH.

12. The UE of claim 8 , wherein the first PRACH overlaps in time domain with the second PRACH, and the total transmission power of the first and second PRACHs exceeds the threshold, a transmission of the second PRACH is dropped.

13. The UE of claim 8 , wherein when the first PRACH overlaps in time domain with the second PRACH, and the total transmission power of the first and second PRACHs exceeds the threshold, the determined transmission power of the second PRACH is reduced such that the new total transmission power of the first and second PRACHs does not exceed the threshold.

14. The UE of claim 8 , wherein the threshold is a maximum power limit.